Deca(4-methylbenzyl)ferrocene and -stannocene

Cyclopentadiene reacts with five equivalents of 4-methylbenzylalcohol (1:5,6 mole ratio) and sodium yielding penta(4-methylbenzyl)cyclopenta-2,4-diene (1), which upon treatment with butyl lithium affords the lithium salt [(4-MeC6H4CH2)5C5]Li (2). The reactions of 2 with FeCl2 and SnCl2 result in the formation of deca(4-methylbenzyl)ferrocene (3) and deca(4-methylbenzyl)stannocene (4), respectively. The 1H and 13C NMR, IR and mass spectra of the new compounds as well as the single crystal X-ray structure analysis of 1 are reported and discussed

SiMenafil I s a Pulmonary Vasodilator in Awake Lambs with Acute Pulmonary Hypertension

Background: Phosphodiesterase type 5 (PDE5) hydrolyzes cyclic guanosine monophosphate in the lung, thereby modulating nitric oxide (NO)/cyclic guanosine monophosphatemediated pulmonary vasodilation. Inhibitors of PDE5 have been proposed for the treatment of pulmonary hypertension. In this study, we examined the pulmonary and systemic vasodilator properties of sildenafil, a novel selective PDE

Best-of-Three Contests: Experimental Evidence

We conduct an experimental analysis of a best-of-three Tullock contest. Intermediate prizes lead to higher efforts, while increasing the role of luck (as opposed to effort) leads to lower efforts. Both intermediate prizes and luck reduce the probability of contest ending in two rounds. The patterns of players‟ efforts and the probability that a contest ends in two rounds is consistent with „strategic momentum‟, i.e. momentum generated due to strategic incentives inherent in the contest. We do not find evidence for „psychological momentum‟, i.e. momentum which emerges when winning affects players‟ confidence. Similar to previous studies of contests, we find significantly higher efforts than predicted and strong heterogeneity in effort between subjects

A Survey of Experimental Research on Contests, All-Pay Auctions and Tournaments

Many economic, political and social environments can be described as contests in which agents exert costly efforts while competing over the distribution of a scarce resource. These environments have been studied using Tullock contests, all-pay auctions and rankorder tournaments. This survey provides a review of experimental research on these three canonical contests. First, we review studies investigating the basic structure of contests, including the contest success function, number of players and prizes, spillovers and externalities, heterogeneity, and incomplete information. Second, we discuss dynamic contests and multi-battle contests. Then we review research on sabotage, feedback, bias, collusion, alliances, and contests between groups, as well as real-effort and field experiments. Finally, we discuss applications of contests to the study of legal systems, political competition, war, conflict avoidance, sales, and charities, and suggest directions for future research. (author's abstract

Ceramic Cutting Tool Tests at Interrupted Machining

Import 29/09/2010Tato bakalářská práce se zabývá testováním keramických řezných nástrojů v podmínkách přerušovaného řezu na simulátoru přerušovaného řezu, který byl zkonstruován na katedře obrábění a montáže. V první části práce je uveden popis keramiky jako obráběcího materiálu a popsány druhy a typy opotřebení řezných nástrojů. V experimentální části je uveden popis vybrané metodiky a detailní popis přípravku pro testování nástrojů při přerušovaném řezu. Jsou zde porovnány čtyři typy keramických řezných destiček od firmy SANDVIK z hlediska schopnosti odolávat rázům při podélném soustružení v podmínkách přerušovaného řezu. Na závěr je vyhodnocení jednotlivý typů, jejich srovnání a diskuze dosažených výsledků.This thesis deals with the testing of ceramic cutting tools in intermittent cutting conditions for intermittent cutting simulator, which was constructed at the Department of machining and assembly. The first part is a description of a ceramic material and machine types and describes the types of cutter wear. The experimental section provides a description of the methodology and detailed description of the testing tools in intermittent cutting. Are compared four types of ceramic cutting plates from Sandvik in terms of ability to withstand shocks when turning the machine under conditions of intermittent cutting. In conclusion, evaluation of individual types of comparison and discussion of results. Are compared four types of ceramic cutting plates in terms of ability to withstand shocks when turning the machine in terms of intermittent cutting.346 - Katedra obrábění a montáževýborn

Ceramic Cutting Tool Tests at Irregular Interrupted Cut

Import 03/08/2012Tato diplomová práce se zabývá testováním keramických řezných nástrojů v podmínkách nepravidelného přerušovaného řezu na simulátoru přerušovaného řezu, který byl zkonstruován na katedře obrábění a montáže. V první části práce je uveden popis keramiky jako obráběcího materiálu. V druhé - experimentální části je uveden popis vybrané metodiky a detailní popis přípravku pro testování nástrojů při přerušovaném řezu. Jsou zde porovnány dva typy keramických řezných destiček od firmy ISCAR a TaeguTec z hlediska schopnosti odolávat rázům při podélném soustružení v podmínkách nepravidelného přerušovaného řezu. Na závěr je vyhodnocení jednotlivý typů, jejich srovnání a diskuze dosažených výsledků.This thesis deals with the testing of ceramic cutting tools in intermittent cutting conditions on an irregular interrupted cut simulator, which was constructed at the Department of machining and assembly. The first part is a description of a ceramic material machining. In the second - the experimental section provides a description of the methodology and detailed description of the testing tools in intermittent cutting. There are two types of matched ceramic cutting inserts from the company ISCAR and TaeguTec in terms of ability to withstand shocks when turning the machine under conditions of intermittent irregular cut. Finally, evaluation of individual types of comparison and discussion of results.346 - Katedra obrábění a montáževýborn

219-234 of ournal & meSi?ic Chemistry

Abstract A series of Cp'(C,H,)ZrCI, and Cp;ZrCl, precatalysts (Cp' = C,Me,H, C,Me,P, CsMe,) together with (C,Hs),ZrCIZ has been investigated in terms of steric and electronic variations and their catalytic activities in combination with methylalumoxane (MAO) towards the polymerization of ethylene are compared. The changes in the steric environment were evaluated on the basis of the structural data available and supplemented by theoretical structural studies on the semiempirical (ZINDO, EHMO) and density functional (DF) level. The X-ray structures of (C,Me,H),ZrCl, ,ZrCl, > (C,Me,P),ZrCl,, which for the most part is inversely proportional to the steric demand of the ring ligands in the metallocene precatalysts except for the phospholyl systems. The lower activities of the phospholyl vs. the tetra-and penta-methylcyclopentadienyl compounds might imply an electronic effect such that the electron withdrawing phosphorus substituent decreases the activity, although further studies are needed to clarify this situation. Emphasis is placed on the control of the polymerization conditions and evaluation of the time-activity profiles. At higher zirconium concentrations an increased precipitation of polyethylene takes place during the course of polymerization and results in a transfer to the heterogeneous phase with a diffusion controlled reaction rate thereby invalidating any activity-comparing studies